Seeking better way to add precise hemispherical caps to a swept curve
Maybe, instead of the native curve bevel, you can use Array and Curve modifiers on a profile segment ..(blue section, below)



The array can have 'Start' and 'End' caps (red and yellow). It's easier to use Constant Offset in the array. Adjust (here, in  Z,) the positions of the caps in Edit Mode, until the  'Merge' in the array takes, before giving the array a Curve modifier.

You can set the count of the array to fit the curve, and parent the curve to the mesh to keep it all together.

This is reasonably reusable, the curve and array can be duplicated together, and the curve edited as you like, the caps will stay in place.

If / When you want to fix the mesh, you can Header > Object > Convert To > Mesh, which will apply all the modifiers at once.